The proliferation of smart mobile devices is leading to an unprecedented increase in mobile data traffic, but the distribution of traffic is not uniform over time. Networks often observe significant variation in utilization levels, mainly triggered by diurnal patterns of human activity; e.g., networks see more utilization during days than nights, cellular base-stations are more loaded during mornings and late evenings in residential areas, whereas base-stations near commercial areas are busy during office hours, etc. In fact, there is high variation in the throughput that a given traffic flow achieves even at short time scales of a few seconds.
Such variation in traffic causes traffic congestion (due to overload) at certain times of day and under-utilization at certain others. Overloaded conditions can adversely impact the quality-of-experience (QoE) of users, especially when streaming videos, and lower the effective yield of network resources. One way of alleviating the traffic congestion is to deliver traffic that users are not actively waiting for (that is, delay-tolerant traffic) during periods of lighter use. Doing so in an effective manner is not straightforward since load at a cellular base station fluctuates even at short time scales.
As such, delivery of digital content to mobile devices over a spectrum (such as 3G spectrum) carries costs for mobile network operators, over-the-top-providers, and end users. Mobile network operators provide bandwidth for delivery of data services. Cellular networks incur significant capital and operational costs, which are increasing significantly due to the rapidly growing demand. Also, cellular wireless spectrum is a scarce and increasingly expensive resource. Consequently, it is important for the operators to extract the maximum yield out of the spectrum owned. The yield of a network deployment is a function of the number of “useful” bytes delivered in time without deteriorating the QoE to users. One way of maximizing yield is to deliver delay-tolerant traffic (or flows) during times when the network has spare capacity. Such delivery will help improve QoE for real-time flows due to lower interference from competing flows. At the same time, spectrum that would otherwise remain unutilized can effectively be put to use.